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Chapter 7 Lesson 4 Solving Inequalities by Adding or Subtracting pgs. 345-349 What you’ll learn: Solve inequalities by using the Addition or Subtraction Properties of Inequality What you’ll learn: Solve inequalities by using the Addition or Subtraction Properties of Inequality
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k Solving an inequality means finding values for the variable that make the inequality true. k You can solve inequalities by using the Addition and Subtraction Properties of Inequalities (pg. 345) This is the same concept as using the Addition/Subtraction Properties of Equations (Lesson 3-3 pgs. 110-111) k Solving an inequality means finding values for the variable that make the inequality true. k You can solve inequalities by using the Addition and Subtraction Properties of Inequalities (pg. 345) This is the same concept as using the Addition/Subtraction Properties of Equations (Lesson 3-3 pgs. 110-111)
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Example 1: Solving an Inequality using Subtraction Solve -13 9 + b Check your solution Write the inequality: -13 9 + b Subtract 9 from each side: -13 9 + b -9 -9 Simplify: -22 b or b -22 To check your solution, try any number less than or equal to -22 Check using -22: -13 9 + (-22) -13 -13 Check: using -30 -13 9 + -30 -13 -21 Check using -20: -13 9 + -20 -13 -11
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Example 2: Solving an Inequality using Addition Solve a - 5 6 Check your solution Write the inequality: a - 5 6 Add 5 to both sides: a - 5 6 +5 +5 Simplify: a 11 Check your result by using any number greater than 11 Check using 12: 12 - 5 6 7 6 Check using 32: 32 - 5 6 27 6 Check using 7: 7 - 5 6 2 6
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Example 3: Graph Solutions of Inequalities Solve h + 4 4 Then graph the solution on a number line. Write the inequality: h + 4 4 Subtract 4 from each side: h + 4 0 - 4 -4 h 0 The solution is h 0 Check: any number greater than 0 I’m using 1 1 + 4 4 5 4 Now graph the solution On a number line. Done on board in class.
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Example 4: Use an Inequality to Solve a Problem Chris is saving money for a ski trip. He has $62.50, but his goal is to save at least $100. What is the least amount Chris needs to save to reach his goal? Explore: We need to find the least amount Chris needs to save Plan: Let x represent the amount he needs to save. Write an inequality to represent the problem. Remember at least means greater than or equal to. x + 62.50 100 Solve: x + 62.50 100 - 62.50 -62.50 x 37.50 So the least amount that Chris needs to save is $37.50
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Your Turn! Solve the inequality, graph your solution, do a check A.c - (-2) 3 B.25 n + (-12) C.g - 1 2 D.k + 9 -21 A.c - (-2) 3 B.25 n + (-12) C.g - 1 2 D.k + 9 -21 2 3 1616 c + 2 3 Check using -1 -2 -2 -1 - (-2) 3 c 1 1 3 25 n + (-12) Check using 40 +12 +12 25 40 + (-12) 37 < n, n 37 25 28 g - 5 + 5 13 + 5 Check using 4 3 3 6 3 4 - 1 2 g 3 2 2 2323 1616 1313 1616 k + 9 -21 Check using -25 - 9 -9 -25 + 9 -30 k -30 -16 -30 5656
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kExtra Practice by the door on your way out. See me if you have questions/problems!
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